On Sunday 22 October 2006 09:09, Robert Hancock wrote:> Andi Kleen wrote:> > Andi Kleen <ak@suse.de> writes:> > > >> I tested it on a NF4-Professional system with 8GB RAM and a single > >> SATA disk. It first did nicely in LTP and some other tests,> >> but during a bonnie++ run it eventually blocked with all> >> IO hanging forever. No output either. I did a full backtrace> >> and it just showed the processes waiting for a IO wakeup.> > > > Hmm, to follow myself up: after a few more minutes the machine recovered> > and i could log in again (overall the stall was at least 5+ minutes> > though)> > > > Not sure whom to blame, the IO driver might be actually innocent> > and it just be one of the usual known but unfixed IO starvation problems.> > > > -Andi> > Hmm.. The system hanging up for 5 minutes

I've actually seen that before on different systems. Sometimesunder some IO loads writes can be really starved for that longand they block the calling process. Normally it only happenedwhen a very slow IO device (like slow USB storage) was involved